For remotely-manipulated maintenance work on conduits and flange joints in processing components such as flange mounted valves or taps in radioactive cells of reprocessing installations, impact wrenches are used for the purpose of releasing or connecting the threaded bolts at the flange joints. In this connection, it has been proposed to join two connecting flanges by through bolts with threaded nuts arranged behind the flanges. The nuts are held in a form-tight manner in appropriate sockets provided on the rear flange so that they cannot rotate. To enable the flange mounted component to be removed from the conduit when the screws of the flange joints have been disconnected, it is necessary for the threaded bolts, once released from the associated nuts, to be pulled out of the bore extending through the flange at the nut side far enough to permit the component which has to be exchanged to be removed from the nuclear processing installation by remote control.
It has been found that, as the threaded bolt connections are released, the threaded bolts which have been threadably disengaged from the nuts corresponding thereto may still be left in the bores extending through the flange at the nut side. Remote-controlled removal of the appropriate length of conduit or component thus becomes difficult or even impossible under this circumstance.